Kent Test style non-verbal reasoning, the puzzles made of shapes and patterns. Every shape here is drawn by the page itself, so there is an endless supply. Instant feedback and an explanation come with each one.
Non-verbal reasoning uses shapes and pictures instead of words. It checks whether a child can spot patterns, and notice how a shape has turned, flipped, grown or changed colour. It does not depend on reading or vocabulary, which is why the 11+ uses it.
The trick is to check one thing at a time: shape, then direction it points, then colour.